Poster 93

Objectives: To test the hypothesis that signal intensity from tibialis posterior tendon is significantly different in patients with tendinopathy and normals and to test whether discrete anatomical locations along the posterior tibialis tendon are sufficiently divergent in signal intensity to determine areas of greatest pathology. Design: Cross-sectional masked analytical study. Setting: Biomedical research facility and image-processing laboratory. Participants: 12 subjects with tibialis posterior tendinopathy include 6 with inhomogeneous signal (partial tear), 4 with tendonitis, 2 with peritendonitis, and 5 control subjects confirmed by magnetic resonance imaging. Interventions: Not applicable. Main Outcome Measures: Postgadolinium-spoiled gradient-echo axial magnetic resonance images with fat suppression of the tibialis posterior tendon were obtained for each subject. Image processing was undertaken to normalize each image on a standard scale (0–4095) to give the same tissue-specific intensity, independent of the scanning protocol and patient. The mean signal intensity was derived for each slice and the peak value chosen as the primary outcome measure and between-group comparisons made at discrete anatomical locations. Results: Throughout the length of the tendon, and at every discrete tendon slice the mean signal intensity was higher for abnormal tendons for 14 slices (mean ± SD abnormal tendon group vs control group, 999±355 and 745±189 at insertion; mean, 833±480 and 569±137 at midlength; mean, 724±294 and 534±175 at ankle wrap-around; mean, 496212 and 379±77 at the proximal ankle region). Mean between-group differences (95% CI) were 254 (−31 to 540) at insertion, 263 (−61 to 588) at tendon midlength, 190 (−60 to 440) at the ankle wrap-around region, and 117 (−33 to 266) at the proximal ankle region. Conclusions: Tendinopathy is quantitatively distinguished from normal tendon using this technique. At discrete anatomic locations including insertion, midlength, ankle wrap-around, and proximal ankle regions, signal intensities are higher than normal values.